What size bed to get after toddler bed?

Hey all, we have another baby coming soon so we will be giving her my daughter's crib and getting her a new bed. I can't decide whether to just get her a twin bed, or get something bigger like a full or queen (that way I won't have to buy another one when she's older).

Zanes in a toddler now and it's going to last him afew more yrs yet, I think he will be fine in it till he's at least 6.
After that I'm getting him a bunk bed that has a double on the bottom and a single at the top.

Zanes a crazy sleeper so I wouldnt trust him in a normal bed right now as they can be pretty high off the floor unless used with a bed guard ofcourse

We did twin size, we did give my now 9yr old our full size when we upgraded to a king finally, that was last year so he was 8. But he often sleeps in his brothers twin bed, he would have loads of room still even if that's what he was in.

I don't intend to ever get mean anything bigger than a normal single. I'm not sure why they'd need a double bed tbh.
Daniel is in a toddler bed at the moment but at Christmas will be being moved to my old single bed. Esther will hopefully move from her cotbed into her single bed at the same time.

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